(Uploaded by Plazi for the Bat Literature Project) Ecological Infrastructures (EIs) form a network of natural and semi-natural areas crucial to support biodiversity in human-altered landscapes. Several indices have been proposed to assess the ecological quality of EIs, but these have been seldom tested using animal biodiversity as a response variable. The Habitat Ecological Infrastructure's Diversity Index (HEIDI) was recently developed to assess the potential of EIs in supporting biological commu­ nities with distinct dispersal abilities. In this study, we evaluated the strength of the HEIDI as a proxy of ant (short-range dispersers) and bat (long-range dispersers) activity in two Mediterranean agricultural areas. For this, we applied a Hierarchical Modelling of Species Communities (HMSC) approach and modelled the multi­ specific response of ant and bat communities to the HEIDI values and to the scores of the individual categories that compose it. We additionally adopted a functional methodological approach by selecting as response vari­ ables the activity of functional guilds, namely animal community regulators, decomposers, and seed dispersers for the ant community, and the activity of echolocation guilds, such as short-range (BAT_SRE), mid-range (BAT_MRE), and long-range echolocators (BAT_LRE) for the bat community. Besides the HEIDI, we also used physiognomic and structural EI attributes, as well as the percentage of the agricultural matrix in the ecological area of influence as covariates in the HMSC approach. Our results showed that the HEIDI formula was partic­ ularly accurate in predicting bat activity (posterior mean estimates, βBAT_SRE = 2.80, βBAT_MRE = 0.61, βBAT_LRE = 2.76), but no significant relation was found between HEIDI values and ant activity. In the context of Mediter­ ranean floodplain management, we recommend that practitioners may use the individual HEIDI categorical scores to identify key habitat features that promote ant and bat activity, such as vegetation and aquatic habitats, whilst final HEIDI values may be broadly used to estimate global bat activity.